Whatawhata hill country research farm (to the west of
Hamilton) in the early 1970s, by Robin Palmer, showed that
the tephra mantle on weathered greywacke had been lost
from steeper slopes by rotational land-sliding (slumping) or
soil creep. He found that on slopes of about 20°, only the
upper horizons of soils are derived from tephra, their lower
Fig. 2.10 Ploughed Allophanic Soils are vulnerable to erosion. Top: wind erosion occurring on a bare soil near Ohakune. Bottom: reduced crop
production on an eroded slope
2.7 Use and Management of Allophanic Soils
37
Hamilton) in the early 1970s, by Robin Palmer, showed that
the tephra mantle on weathered greywacke had been lost
from steeper slopes by rotational land-sliding (slumping) or
soil creep. He found that on slopes of about 20°, only the
upper horizons of soils are derived from tephra, their lower
Fig. 2.10 Ploughed Allophanic Soils are vulnerable to erosion. Top: wind erosion occurring on a bare soil near Ohakune. Bottom: reduced crop
production on an eroded slope
2.7 Use and Management of Allophanic Soils
37